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June 21,1927. L 1,633,049 H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS filed May 22, 1926 2 Sheets-Sheet 1 June 1927. 1 ,633,049 7 1 H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed May 22. 1926 2 Shets-Sheet 2 w \N N 3 g Qm f c -L Q Um i MR Q QM wm Patented June 21, 1927.

UNITED STATES 1,633,049 PATENT" OFFICE.

HOWARD ANTHOMPSON, OF EDGEWOOD BOROUGH, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH 8t SIGNAL COMPANY, OF S W ISSVALE, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIA.

RAILWAY-TRAFFIC-CONTROLLING APPARATUS.

I Application filed May 22, 1926. Serial No. 110,923.

My invention relates to railway traffic controlling apparatus, and particularly to apparatus of the type comprising train car ried governing means controlled at least in partby alternating currents which flow through the track rails.

One object of my invention isthe provision, in apparatus of thetype described, of means for supplying energy to the train carried means in accordance with train controlling current in the trackway, but which will not supply energy to such means in accordance with alternating currents flowing in adjacent transmission lines or in adjacent tracks etc. p

, Iwill describe two forms of railway traffie controlling apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic view illustrating one form of railway traflic controlling apparatus embodying my invention. Fig. 2 is a view showing a modified form of the apparatus illustrated in Fig. 1 and also em'bodyingmy invention. F g. 3 1sa View showing, in front elevation, the receiver E forming a part of the railway trafiic controlling apparatus shown in the preceding views and also embodying my invention.

Similar referencecharacters refer to sim ilar parts in each of the three views.

Referring first to Fig. 1, the reference characters 1 and 1 designate the track rails of a stretch of railway track over which traflic normally moves in the direction indicated by the arrow. These track rails are divided, by means of insulated joints 2, into a plurality of successive track sections AB, BC, etc. I Each track section is provided with a track relay designated by the reference character D with an exponent corresponding to the location and connected across the rails adjacent the entrance end. of

the corresponding section. Each track relay ,plylng each track section-with loop current D is responsive to the relativepolarity of the current supplied thereto, and controls an associated line relay designated by the reference character IQwith a suitable distinguishing exponent. Referring, for example, to relay K, this relay is supplied with energy from secondary 7 of a line transformer Q Whenrelay D is-energized in either direction. The prima'ryS of trans:

former Q, .is constantly supplied withal-, ternating current from a suitable source of energy, such as an alternator M, over line wires 3 and 3 Each of the remaining relays Kis supplied with energy from the-secs ondary 7' of an adjacent transformer Q, over the contacts of the corresponding track relay in the same manner that relay K is controlled by relay D Each track section is also-provided with a track transformer designated by the reference character T with an exponent corresponding to the location and comprising a secondaryw l connected across the rails adjacent the exit end of the corresponding section throughthe usual impedance 6. The

primary 5 of each track transformer T is supplied with current of one relative polarity or the other over contacts 15 and 16 of the adjacent line relayK from the secondary 7 of the corresponding transformer Q. As willbe lain from the drawing, the rails of each section are provided with track circuit current of one relative polarity, which I will term normal relative polarity, when the line relay K for the section next in advance is energized. Referring for example to section A-B, when relay K is energized, track circuit current of normal relative olarity is supplied to the rails of section 1 -By Under these conditions contact 42 of relay D is. swungto the left. When relay K is tie-energized, however, back contacts 15 and 16 are closed and track circuit current of the opposite relative polarity,.which I shall term reverse relative polarity, is supplied to the rails of section A,B. Under these conditions contact 42 of relayD is swung to the right. It will be observed that the track circuit current thus supplied to each section flows through the two rails in series so that. this track circuit current flows in opposite directions in the two track rails at any instant.

Means are also provided for at times supwhich flows through the two rails of the section in parallel. For thispurpose each section is provided with an impedance 12, here as a resistor, connected across: the rails adjacent the exit endef the section. A

nd resistor l liis connected across the rails at an intermediate point in each sect on,

The immediate source of loop current for" each soctio'ir'is a loop. transformer, designated by the reference "charactecL with an'exponent corresponding to the location and located adjacent the exit-end o f the;section. :Qurrent supplied by this transformer flows through the rails of thesection in. parallel and returns to the transformer through an auxiliary conductor designated-by thereference character X with an appropriate disi'zii'iguisl'iing exponent-- wliichis connected to the mid-point of iinpedance12 and extends throughout the section "between the track rails 1 and 1 Referring particularly to section AB, when relay K is energized loop current "flows fronr secondary 11 of transformer L through wire19, frontcontatt 18 of relay K wire 20. impedance 13, rails 1 and 1 of section in parallel, iinpec'lance 12. auxiliary conductor X and wire .ZLback to secondary11 of transformer L When this circuit is closed, loop curreiit is supplied to the rails of section A-B andto conductor X throughout the length of this section. \Vhenrelay K is de energizcd, the circuit just traced is opened, and

current flowsfrom secondary of trans former L ,through wire 22, back contact, 17 of relayK wire 23, impedance'let, rails 1 and 1'" of section AB in parallel, impedance 12, and thence through auxiliary conduotor X and wire 24L back to secondary 10 of transformer L hen this circuit is closedfloop current is supplied to the rails of the section and to conductor'X only between point A and the points of connection of impedance let andwire 24- wi-th the rails of the section and the conductor X respectively. Itjfollows that section AB is suppliedwvith loop current throughout the length of the section or throughout a portion only of the section according as'th'e line relay K is" energized or de-energized respectively. It should be pointed out, however, that when the rails are being supplied with loop current the currentwhich flows down the rails in parallel returns through the auxiliary conductor X, and that the 'di rection of'the tlo'opcurrent in the conductor is opposite tothedirection of'the loop current in 'the rails'ati a'point-"in the section at any inst-ant.

As shown in the drawing-the section to the right of point (his occupiedloy a train indicated i liagrammaticaflly,'at' V. Relay D is therefore (ole-energized so that contact '42 assumes an 'intermediatepo on. and 'relay K is de -energized. Section *B C --is witlitrack c can current f reverse :re'lative polaritycandj loop 5 euri 11f is 'su fjthe "be tween point B and the-p "of-cons ron at resistor ls, this loop current also flowing through they conductor-X between the impedance 12 and the point of connection of polarity .and lo op current is supplied to the "rails of this section and to the conductor X throughout thelength of the section. In similar manner relay K is energized so that track circuit current of normal relative polarityis' supplied to-the rails of the section to the left of point A and loop current is supplied to the rails of this section and to the, conductor associated therewith.

The section to the left of point A is occupiedby a second train indicated at V? and provided withtrain carried 'means suitable for cooperation with the traclrwayc apparatus described hereinbet'ore. he traincarrie'dmeans comprises a track receiver F coinprisingtwo magnetizable cores and 30 carried by'the train in advance of the forward axle 28 and located in inductive relation with the two track rails 1 and 1 respectively. Core 30 is provided with a Winding 31 and core 30 is provided with a similar winding 31, the two windings being connected in series in such manner that the voltages induced in these windings by track circuit. current flowing in opposite directions in the two track rails at an instant are additive. The windings 31 and 31 are connected, through an amplifier 32, with one winding 33 of an induction motor rclay P. i

The train V is also provided with a loop receiver designated by the reference char actor-E which may be located at a convenient place. on the train, as between the locon'iotive and tender. This receiver is similar to the track receiver but comprises alsoa third magnetizable core 30 located in inductive relation wi'tlrthe auxiliary con 'ductor extending through the tra-clrway and carrying awinding 31". This winding; is connected in series with the associated wind ings 31 and 31 in such manner that the voltages induced in these three windings by loop current, which flows in one direction in the two track rails and in the other direction in the auxiliary conductor'at an insta'nt.-areadditive. The windingsof ,recei'ver Eare connected;through an amphfier' 34, witlr't-he otherwinding 35 ofrelay P. ilVhen the train V occupies a stretch "of track which is'b'eing suppliedwith track circuit currentof normal relative polarity and with loop current. the relative polarityof :andlamp G is then supplied with current "from a suitjabl'e' sourceof -energy,- such as b e y Lamp G therefore becomes lighted to indicateprocee'd. when the relative polarity of "either the loop current.

the circuitfor lamp Y which then displays a caution indication. Should the supplyof either trackc'ircuit current or loop current to the stretch of track occupied by a train become interrupted, relay P would become de-energized and contact 36 would occupy an intermediate positiongin which the cir cuit for a third lamp B would be closed, thereby lighting this lamp to give a stop indication. a I a I willnow assume that the train 'V proceeds through thestretch' of track shown in the drawing. When the train enters section AiB-l/h6 track circuit current of'normal relative polarity and tlieloop current supplied to thissectionenergize relay P so that contact 36 remains in the left hand position whereinitenergizes lam G to give a proceed indication. When t e train enters section 13 C however, reversal of the relative polarity of the track circuit current supplied to the rails of'this section causes contact36 ofrelay P to swing to the right, thereby lighting lamp .Y which dis plays a caution indication. Afterthe train passes the point of connection of resistor 14 with the railsof section BC;and of wire 24 with the conductor X the inter ruption of loop current causes winding 35 of relay P to become de-energized so that contact 36 occupies its intermediateposition, completing the circuit for lampR which displays a stop indication. Should the train enter the section to the right otpointC the interruption of track circuit current due to the shunting effect of the wheels and axles o'ftrain V, would de-energize winding 33 of relay Pso that the trainwould continue to receive a stop'indication'.

best shown in Fig.3 the fluxes due to loop current in the rails 1 andl encircle the rails in the same direction, as indicated at 39 and 40, and pass through the cores 30 and 30*, of the receiver E. The flux which surrounds'the conductor X, as indicated at 41, traverses the core 30 in the opposite direction; however, and as explained hereinbefore, the windings of the'receiver are so connected in series that the voltages induced in these windings by the loop current in the trackway are additive. If, however, the

' receiver is in the path of a stray 'flux', such forexample as. that due to alternating current in a transmission line or a second t'rack parallel to the rails 1 and 1?, this flux would thread through the three cores 30, 30mm 30 in the same direction. The voltages induced in windings 31 and 31 by this'stray flux would tend to oppose the voltage induced in winding 31 by the stray flux. By suitably proportionin the parts, the apparatus is arranged so that the resulting volt-- age supplied to winding 35 of relay P as a result of the separate voltages induced in the winding of receiverE by this stray flux is reduced to a negligible amount. It is therefore impossible, with apparatus embodying my invention, for stray flux due to current flowing in an adjacent conductor to create in the windings of the loop receiver, voltages which might result in improper operation of the traincarrfed apparatus.

Referring now to Fig. 2, the traincarried apparatus is exactly the same as that illustrated in Fig. 1, but the trackway apparatus has been modified so that track circuit current of normal relative polarity is constantly supplied to the rails of each section by the track transformer-T, the primary of which is supplied with alternating current from line wires 3 and 3 The relative polarity of the current supplied to primary 9 of each loop transformer L is controlledby pole changing contacts 25 and-26 on the adjacent track relay -D. Referring particularly to section -A- B, when relay D is energized, current of normal relative polarityis supplied; to primary 9 of transformer.L over contacts 25-and 26. 1 At" the same time loop current is supplied from secondary ll of transformer L over front contact 27 of track relay D to the rails otsection A-B and to conductor X4 throughout thelength of the section. NVhen relay D is. de-energized, however, current of reverse relative polarity is supplied to the primary9 of transformer L and loop current is supplied from secondary 10 of this transformer over back contact 28 of relay D to the rails of section A-B, and to conductor X4 between point A and the points of connection of resistor 14 and wire 24 with the rails and the conductor, respectively. The control of loop current for each of the remaining sections is similar to the cont-rolof loop current for section A--B. The operation of the apparatus illustrated in Fig. 2 is similar to the operation of the apparatus shown in Fig. 1, it being noted that in Fig. 2, the caution indication is obtained by a reversal of the relative polarity of the loop current instead of a reversal of the track circuit current as inFlg. 1; The receiver E is 1m- Inune'to the effects of stray fluxes however, I

as explained in connection with Fig. 1.

Although I have herein shown and described only two forms of railway traflic controlling apparatus embodying my inven tion, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

EHELViIlgJthUS described my invention, what I clalm s: i

.1. In combination, a stretch of railway "tracii having an auxiliary conductor, means for 'supplying thestretch with loop current whichfiows at a given instant in one direction in therails ot the stretch and in the other dir ction through the conductor, a train carried receiver comprisingthree winds in ings one in inductive relation with each rail and one in inductive relation with said conductor, said windings being connected in series in such manner that the voltages in duced therein by loop current flowing in the trackway are additive, and governing means responsive to the voltages induced in said windings.

2. In combination, a stretch of railway track having an auxiliary conductor, means '1" for supplying the stretch with'loop current.

which flows in one direction in the rails of the stretch and in the other direction throughthe conductor, a train carried receiver comprising two windings one'located in inductive relation with each track rail and a third winding located in inductive relation with said conductor, said windings being connected in series in such manner that the voltages induced therein by loop current ilowing in the tra'ckway are additive but that the voltages inducedin said two windings due to current flowing in a conductor outside the traclrway opposes the voltages-induced in said thirdwinding by such current, and governing means -responsive to the voltages induced in said wind- IIIgS.

3. In combination, a section of railway track having an auxiliary conductor, means to for connecting said conductor with the rails at one point in the section, a source of energy having one terminal connected with the rails and the other terminal connected with said conductor at another point int-he section, a train carried receiver comprising two windings inductively related to the two track rails respectively and a third winding inductively related to said conductor, said windings being connected in series in such manner that the voltages induced in said three windings by currents flowing in one direction in the track rails and in the other direction in the conductor are additive, and governing means responsive to, the voltages induced in said windings. r

4. In combination, a section of railway track having an auxiliary conductor, means for connecting said conductorwiththe' fails at one point in the section, a source of energy, means for connecting said source between said conductor andithe r'ailsata second point or a third. point depending upon trafiic conditions, a train carried'receiver comprising. two windings ,in'. .indue- 9 tive relation with the twontrack; re-

directio Ph ...;lli l, 9.0. 6

spectively and a third winding inductive relation with said conductor, said three windingsjbeing connected in series in such manner thatthe voltages induced therein by currents flowing in onedirection incthe conductor and in the other direction} in; the rails are additive, and governing means responsive to the voltages induced in said windings.

5. In combination, a stretchof railway track having an auxiliary conductor, means for at tiines supplying alternating current to the conductor and at least one rail so that current flows in opposite directions through said conductor and rail at an instant, a train-carried receiver comprising a winding inductively related with said conductorand a second winding inductively related with said rail, said windings being connected in series in such manner that the voltages induced therein 'byialternating currents flowing in one direction in said rail and in the other direction in said conductor are additive, and governingmeans responsive to the voltages induced in said windings.

6,111 combination,- a section of railway track; having an auxiliary conductor, means for connecting said conductor with the rails at one point in the section, a source of energy'havi ig one terminal connected with the rails and the other terminal connected with said conductor at another point in the section, a second source of energy connected across the rails of the section, a train carried receiver comprising two windings 'in inductive relation with the track rails respectively and connectedin series in such manner that the voltages induced in said windings currents whichfiow in opposite directions in the two track rails at an instant are additive, a second train carried receiver comprising two windings in inductive relation with the twotrack rails respectively. and a third winding in inductive relation with said conductor, said three windings being connected in series in such manner that the voltages inducedvtherein by currents which flow in the same direction in. said track rails and in the opposite direction in said conductor are additive, and governing means responsive to the voltages .delivered by said receivers.

t7. In combination, a stretch of track having an auxiliaryconductor, a train carried receiver comprising two magneti'zable cores one located over each rail and a ,thlrd magnetizable core over said 7 conductor means for at t mes supplyingthe} trackway w th alternating loop currentwhichfiows. in one direction in said rails and in .the other direction in said. conductor Iat 'an instantso that the fluxes in said corespass in one "direction in said two cores j and in, the other ra a wer three windings one on each said core all connected in series in such manner that the voltages induced in such windings by the alternating fluxes in said cores are additive, and governing means responsive to the voltage delivered by said'receiver.

8. In combination, a stretch of railway track having an auxiliary conductor, means for supplying the stretch with loop current which flows at a given instant in one direction in the rails of the stretch and in the other direction through the conductor,

means for supplying therails of the stretch with track circuit current which flows through the two rails in opposite directions, a train carried receiver comprising three windings one in inductive relation with each rail and one in inductive relation with said conductor, said windings being connected in series in such manner that the voltages induced therein by loop current flowing in the trackway are additive, a second receiver comprising'two windings in inductive relation with the two track rails and connected in series in such manner that the voltages induced therein by alternating current flowing in opposite directions inthe track rails are additive, and governing means responsive to the voltages delivered by said receivers.

In testimony whereof I afliX my signature.

HOWARD A. THOMPSON. 

